Methods and apparatus for controlling the current supplied to light emitting diodes
Methods and apparatus for controlling current to an LED light source in a lighting device are described. In some embodiments, a warm dim light output is achieved. In an exemplary embodiment, a light emitting diode (LED) circuit includes two or more circuit branches coupled in parallel across a two terminal direct current (DC) voltage input including a positive input terminal and a negative input terminal; each of the two or more circuit branches including a set of light emitting diodes, each of said set of light emitting diodes including at least one light emitting diode; and at least one of said circuit branches including a current control circuit that controls the current passing through each of said two or more circuit branches.
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The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/525,334 filed on Jun. 27, 2017 which is hereby expressly incorporated by reference in its entirety.
FIELDThe present application relates to LED (Light Emitting Diode) lighting methods and apparatus, and, more particularly to LED circuits for controlling the current supplied to LEDs in a lighting device.
BACKGROUNDFor decades, individuals have become accustomed to having a variety of incandescent lights with different powers. A lamp is an electrically energized source of light, commonly called a bulb or tube. An incandescent lamp is one in which light is produced from an incandescent light source such as for example an incandescent light bulb. Light emitted or produced from an incandescent light source is a kind of light that provides individuals with a general feeling of felicity. Generally speaking, the lower the power supplied to the incandescent lamp, the lower the color temperature of the light output from the incandescent lamp. As a result, people have a warmer perception to the light with low color temperatures. For a given incandescent lamp, the lower the power being provided to the lamp (which occurs when it is dimmed), the lower the color temperature of the emitted light.
The Color Temperature (Correlated Color Temperature—CCT) is a number indicating the degree of “yellowness” or “blueness” of a white light source. Measured in Kelvin, yellowish-white (warm) sources, like incandescent lamps, have lower color temperatures in the 2700K-3000K range; white and bluish-white (cool) sources, such as cool white (4100K) and natural daylight (6000K), have higher color temperatures. Correlated Color Temperature is the absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source.
When the incandescent lamp is dimmed, it is possible to reduce the light output. It is done by reducing the average lamp voltage (e.g., by phase cut dimming) to reduce the average lamp power. As a result, the filament temperature is also reduced, and thus the light emitted by the lamp changes to a lower color temperature. For example, given a standard 60 Watts incandescent lamp, when it operates at 100% light output, its color temperature is approximately 2700K. However, when it is dimmed to 4% light output, its color temperature is reduced to about 1700K. As the color temperature follows the traditional blackbody line in the chromaticity diagram, a lower color temperature gives an individual a reddish impression, which is associated with a warmer, more comfortable, and more pleasant atmosphere.
Recently, based on the fact that a light emitting diode (LED) is more efficient on transferring electrical energy to light and has longer working life, a new trend is to use a LED light source in place of an incandescent light source. To do so, the light source device not only includes one or more LEDs but also a driver that can accept the input voltage for the incandescent light source that needs to be replaced, and then convert the input voltage to a LED-operable current. LEDs are designed to provide a standard light output when they are operated at the nominal constant current. Dimming LEDs can be achieved by reducing the current input to the LED or LED module, but it will not change the color temperature of the light output. An LED module being either a single LED device or a group of self-contained LED devices designed either to function on their own or to plug into a compatible LED fixture.
As the light level drops, LEDs generally maintain the same color temperature (CCT) that they exhibit at full power. Incandescent and halogen lamps dim to a warm CCT at lower levels which individuals prefer and find aesthetically pleasing. With many drivers for luminaires and LED lamps capable of supporting dimming, dim-to-warm CCT capability is a feature that is desirable for LED lamps. The functionality is generally achieved by having two or more different LED strings with each string having different color temperatures. For example, one string of LEDs emitting white light and the other string of LEDs emitting red or amber light with the two LED strings in close proximity and the light emitted from each of the LED strings being mixed together, e.g., with the light emitted from the two LED strings passing through a mixing lens. The use of multiple separate LED strings in known systems requires a separate driver channel to control each separate LED string. As the overall drive current is reduced, the percentage of energy supplied to the red LED string is raised relative to that supplied to the white LED string. This results in an LED lighting product that delivers light in the range of 2700K-3000K CCT when operated at full power yet smoothly reduces the CCT to the 1800K range at the lowest light levels. A problem with this dim-to warm LED capability is that it requires multi-channel drivers one for each LED string, e.g., a dual-channel driver for a lighting product with a red and white LED string, and additional LEDs. The additional channel drivers add more components resulting in higher component costs, manufacturing and assembly costs, and lowers the reliability of the product as there are more components which can fail.
In view of the above it should be appreciated that there is a need for methods and/or apparatus which can support a variety of LED lighting sources and configurations. Furthermore, there is a need for methods and/or apparatus such as for example, LED lighting circuits, that can cheaply and/or efficiently be used to supply current to LED modules. There is also a need for methods and/or apparatus such as LED circuits that can simulate and/or mimic the color temperature of the light out of incandescent lamps. There is a need for cheaper and/or more reliable LED circuits that do not require separate LED drivers for each LED string. There is a need for LED circuits that can produce a warm to dim lighting output in a more efficient and/or cheaper and/or more reliable manner.
SUMMARYThe present invention is directed to various features relating to methods and apparatus for controlling current supplied to LEDs in a lighting device. The present invention is further directed to LED circuits that can be used to control the current supplied to two or more LEDs to simulate a warm dim lighting output using a single current control circuit while receiving power on a single pair of input terminals. The present invention is also directed to an LED circuit that does not require separate LED driver circuits for each LED string included in the LED circuit. Various embodiments of the present invention address one or more of the problems described above.
While various features and elements are described in this summary all features and elements are not necessary or required for all embodiments of the invention. In one particular exemplary embodiment a Light Emitting Diode (LED) circuit includes: two or more circuit branches coupled in parallel across a two terminal direct current (DC) voltage input including a positive input terminal and a negative input terminal; each of the two or more circuit branches includes a set of light emitting diodes with each of the set of light emitting diodes including at least one light emitting diode, and at least one of the circuit branches including a current control circuit that controls the current passing through each of said two or more circuit branches.
In some embodiments, the current control circuit controls the current flow through the second circuit branch to vary disproportionately with respect to the current flow through the first circuit branch in response to a change in the value of the DC voltage.
In some embodiments, only one of the two or more circuit branches in the LED circuit includes a current control circuit.
In some embodiments, the two or more circuit branches includes only two circuit branches a first circuit branch including a first set of LEDs and a second circuit branch including a second set of LEDs, the first circuit branch not including a current control circuit and the second circuit branch including said current control circuit.
In some embodiments, the current control circuit includes at least two resistors, a shunt regulator, and a transistor. The transistor may be an NPN transistor with the LED circuit configured so that the NPN transistor is operated in a non-saturation amplifier mode.
In most, but not all embodiments, at least one of the one or more LEDs in the first circuit branch emit light having a first correlation color temperate characteristic and at least one or more of the LEDs in the second circuit branch emit light having a second correlation color temperature characteristic with the first and second correlation color temperature characteristics being different.
In some embodiments, in order to change the color temperature of the light output from a lighting device, the LED circuit uses at least two different color temperature LEDs in the LED circuit located within close proximity to one another. By controlling the current going through the different color temperature LEDs, the light emitted from the LED circuit can be made to simulate or mimic the change of color temperature from high to low the same as or similar to the light emitted from a traditional incandescent lamp as it is dimmed. Furthermore, the present invention is not limited to only simulating a change of color temperature from the high to low CCTs but also allows for simulating a change of color temperature from low to high CCTs.
In another embodiment, a lighting device includes a light emitting diode (LED) driver circuit having a positive voltage output terminal and a negative voltage output terminal; and a light emitting diode (LED) circuit. The LED circuit includes two or more circuit branches coupled in parallel across the positive output terminal and the negative output terminal with each of the two or more circuit branches including a set of light emitting diodes and each of the set of light emitting diodes including at least one light emitting diode, and at least one of the circuit branches including a current control circuit that controls the current passing through each of the two or more circuit branches. In some such embodiments, at least one of the LEDs in the first circuit branch emits light having a different CCT than the light emitted from at least one of the LEDs in the second circuit branch. In some embodiments, the current flowing through the first circuit branch and the second circuit branch are different.
Numerous additional features, benefits and embodiments are discussed in the detailed description which follows.
The LED circuit 100 includes two circuit branches coupled in parallel across a positive and negative pair of direct current (DC) input terminals 102 and 104 respectively. The first circuit branch includes a current control circuit 106 and an LED D1 110. The second circuit branch includes a current control circuit 108 and an LED D2 112. The LED D1 110 and LED D2 112 both have an anode and a cathode terminal illustrated in LED circuit 100 of
LED circuit 200 of
LED circuit 300 of
In some embodiments, the LED circuits 100, 200 and 300 of
The LED circuits 100, 200 and 300 receive power from an LED driver or power supply source that generates DC output voltage and provides LED current to the LED circuits 100, 200 or 300 at the positive and negative input terminals 102, 104; 202, 204; or 302, 304. The LED driver is a power supply that allows for an adjustment of the LED output current received from an external source such as, for example, a dimmer in both forward phase cut (TRIAC) or reverse phase cut (ELV) or a 0-10V low voltage dimming controller. The LED current output from the LED driver supplies the power to the LEDs in the first and second circuit branches (LED D1 110 and LED D2 112 in LED circuit 100, LED D1 208 and LED D2 210 in LED circuit 200, and the LEDs in LED string set 310 and 308 in LED circuit 300. Current I is illustrated as flowing into the LED circuits 100, 200 and 300 via the positive LED terminal. The current I is then split and current I1 flows through the LEDs included in the first circuit branch and the current I2 flows through the LEDs in the second circuit branch. The current I=I1+I2. As previously discussed, the first circuit branch includes at least one LED for generating light with a first color temperature and the second circuit branch includes at least one LED for generating light with a second color temperature that is different than the first color temperature.
The current control circuits 106, 108, 206, and 306 are used to change the branch currents I1 and I2 flowing through the LEDs in the first circuit branch and the second circuit branch. For example, with respect to LED circuits 200 and 300, the current control circuit 206 in LED circuit 200 and 306 in LED circuit 300 attempt to maintain the current I2 current level that goes through the LEDs in the second circuit branch when the LED driver reduces the total current I supplied to the LED circuit 200 or LED circuit 300 and as a result I2 will change to a value that is not I1 even if both the first and second circuit branches have the same number of LEDs. With the different currents I1 and I2, when the LED driver is dimmed or undimmed from a change in a dimmer control that is controlling the LED driver, the output current I is reduced or increased then the currents I1 and I2 will be changed and the light output from the LED circuit 200 or 300 will display a color change when one LEDs CCT is brighter than another LED CCT thereby simulating the CCT changes of incandescent lamps when dimmed. For example, when the input current I is decreased, the current I1 flowing through the LEDs in the first circuit branch is decreased as the current I2 flowing through the LEDs in the second circuit branch attempts to maintain the I2 current level before the decrease in the input current I. As a result, the light emitted from the LEDs in the second circuit branch will be brighter than the light emitted from the LEDs in the first circuit branch in which the current level I1 has decreased.
The LED circuit 400 of
The LED circuit 400 includes two circuit branches, a first circuit branch and a second circuit branch. The two circuit branches of the LED circuit 400 are coupled in parallel across a positive and negative pair of direct current (DC) input terminals 402 and 404 respectively. The first circuit branch includes LED string set 410 and does not include a current control circuit. The LED string set 410 includes a plurality of LEDs 420, 422, 424, 426, 428 and 430. The plurality of LEDs in the exemplary LED set 410 are connected in series. The first circuit branch also includes an optional resistor R1 442 connected in series with the LED string 410. The LED string set 408 includes LEDs 432, 434, 436, 438 and 440. The plurality of LEDs in the exemplary LED string set 408 are connected in series. The second circuit branch includes a current control circuit 406, LED string set 408, and optional resistors R4 444 and R5 446. The optional resistors R4 444 and R5 446 are connected in series. The LED string 410 and the resistors R4 444 and R5 446 are connected in series. The current control circuit 406 is coupled to the positive input terminal 402 and the LED string 408. The LEDs included in the LED string sets 408 and 410 have an anode and a cathode terminal illustrated in LED circuit 400 of
One or more LEDs in LED set 410 emit light with different CCT characteristics than the LEDs in the LED set 408. The current control circuit 406 includes a first resistor R2 412 with an exemplary value of 1 kilo ohm, a shunt regulator U1 418, a transistor Q1 416, and a second resistor R3 414 with an exemplary value of 51 ohms. The transistor Q1 416 in the exemplary embodiment is a Micro Commercial Components S8050 NPN transistor. The shunt regulator 418 in the exemplary embodiment is a TL 431 programmable shunt regulator. A block diagram, symbol showing reference terminal, cathode and anode terminal, and providing electrical characteristics of the TL 431 shunt regulator are shown in
The components of the LED circuit 400 are electrically connected as shown in
In some embodiments, the LED circuit 400 is included in an LED circuit module incorporated into a lighting apparatus, device, fixture or system.
Diagram 500 of
Box 512 shows the relationship between the total current I 502 and the current I1 504 and I2 506. As shown in box 512 of
In order to make the LED strings 410 and 408 generate two kinds of light with distinguishable colors, the current I2 flowing through the LEDs in the LED string 408 is set to a value that is different from the current I1 flowing through the LEDs in the LED string 410. This is controlled by the shunt regulator U1 418 and the transistor Q1 416. The current I2 506 as shown in box 514 is equal to the voltage across resistor R3 (VR3) divided by the value of the resistor R3 412, i.e., I2 506=VR3/R3. As also shown in box 514, VR3=VREF=2.495 V which is the typical reference input voltage for the TL 431 as shown in
Diagram 600 of
Diagram 700 of
Diagram 800 of
Table 900 of
Table 1000 of
Table 1100 of
Table 1200 of
The plot 1300 of
LED lighting device 1400 shown in
LED Circuit Embodiment 1. A light emitting diode (LED) circuit comprising: two or more circuit branches coupled in parallel across a two terminal direct current (DC) voltage input including a positive input terminal and a negative input terminal; each of said two or more circuit branches including a set of light emitting diodes, each of said set of light emitting diodes including at least one light emitting diode; and at least one of said circuit branches including a current control circuit that controls the current passing through each of said two or more circuit branches.
LED Circuit Embodiment 2. The LED circuit of LED Circuit Embodiment 1, wherein said LED circuit consists of a two power terminal input, said two power terminal input being said positive and said negative input terminals.
LED Circuit Embodiment 3. The LED circuit of LED Circuit Embodiment 1, wherein said LED circuits consists of a plurality of circuit branches and only one of said circuit branches including a current control circuit.
LED Circuit Embodiment 4. The LED circuit of LED Circuit Embodiment 1, wherein said current control circuit controls the current flow through the second circuit branch to vary disproportionately with respect to the current flow through the first circuit branch in response to a change in the value of the DC voltage.
LED Circuit Embodiment 5. The LED circuit of LED Circuit Embodiment 1, wherein only one of said two or more circuit branches includes a current control circuit.
LED Circuit Embodiment 6. The LED circuit of LED Circuit Embodiment 1, wherein said current control circuit indirectly controls the current flow through the circuit branch in which the current control circuit is not included.
LED Circuit Embodiment 7. The LED circuit of LED Circuit Embodiment 1, wherein said two or more circuit branches includes only two circuit branches a first circuit branch including a first set of LEDs and a second circuit branch including a second set of LEDs, said first circuit branch not including a current control circuit and said second circuit branch including said current control circuit.
LED Circuit Embodiment 8. The LED circuit of LED Circuit Embodiment 7 further comprising: wherein said positive input terminal is coupled to: (i) an anode of a first LED included in the first set of LEDs in the first circuit branch and (ii) said current control circuit, said current control circuit being coupled to an anode of a second LED included in the second set of LEDs; and wherein said negative input terminal is coupled to a cathode of a LED included in said first set of LEDs and to a cathode of an LED included in the second set of LEDs.
LED Circuit Embodiment 9. The LED circuit of LED Circuit Embodiment 8, wherein said current control circuit comprises: at least one resistor (R2); a shunt regulator (U1); and a transistor (Q1).
LED Circuit Embodiment 10. The LED circuit of LED Circuit Embodiment 9 wherein said shunt regulator (U1) is a programmable shunt regulator.
LED Circuit Embodiment 11. The LED circuit of LED Circuit Embodiment 8 wherein said current control circuit consists essentially of two resistors (R2 and R3), a shunt regulator (U1), and a transistor (Q1).
LED Circuit Embodiment 12. The LED circuit of LED Circuit Embodiment 8 wherein said current control circuit consists of two resistors (R2 and R3), a shunt regulator (U1), and a transistor (Q1).
LED Circuit Embodiment 13. The LED circuit of LED Circuit Embodiment 9, wherein said LED circuit is configured so that said transistor (Q1) is operated in a non-saturation amplifier mode.
LED Circuit Embodiment 14. The LED circuit of LED Circuit Embodiment 13: wherein said at least one resistor includes at least a first resistor (R2) and a second resistor (R3), said first resistor (R2) having a first terminal and a second terminal, said second resistor (R3) having a first second resistor terminal and a second second resistor terminal; wherein said transistor (Q1) is a NPN transistor having a collector terminal, an emitter terminal and a base terminal, wherein said shunt regulator (U1) includes a reference terminal, an anode terminal and a cathode terminal; wherein said positive input terminal is coupled to the collector of the transistor (Q1) of the current control circuit and the first resistor first terminal (R2); wherein said collector terminal of said transistor (Q1) is coupled to the first positive input terminal and to the first resistor (R2) first terminal, said base terminal of said transistor (Q1) being coupled to the first resistor (R2) second terminal and to the shunt regulator (U1) cathode terminal, said emitter terminal of the said transistor (Q1) being coupled to the shunt regulator (U1) reference terminal and the second resistor (R3) first terminal; wherein said second resistor (R3) second terminal is coupled to the shunt regulator (U1) anode terminal and to an anode terminal of said second LED (D7) included in said second set of LEDs.
LED Circuit Embodiment 15. The LED circuit of LED Circuit Embodiment 14, wherein said first set of LEDs includes a first string of LEDs connected in series, said first string of LEDs including the first LED (D1); wherein said second set of LEDs includes a second string of LEDs connected in series, said second string of LEDs including the second LED (D7).
LED Circuit Embodiment 16. The LED circuit of LED Circuit Embodiment 15, wherein said DC voltage is applied to the positive and negative input terminals from a single external power supply source located outside of the LED circuit.
LED Circuit Embodiment 17. The LED circuit of LED Circuit Embodiment 16, wherein said first set of LEDs includes an LED that emits light having a first color temperature and said second set of LEDs includes an LED that emits light having a second color temperature, said first and second color temperatures being different.
LED Circuit Embodiment 18. The LED circuit of LED Circuit Embodiment 17, wherein said current control circuit controls the current flow through said first and second circuit branches so that the combined light emitted from the first and second set of LEDs simulates the output of an incandescent lamp light output.
LED Circuit Embodiment 19. The LED circuit of LED Circuit Embodiment 18 wherein said first circuit branch further includes at least one resistor (R1) including a first terminal and a second terminal, said first terminal being coupled to the cathode terminal of an LED included in the first set of LEDs, said second terminal being coupled to the negative input terminal.
LED Circuit Embodiment 20. The LED circuit of LED Circuit Embodiment 19, wherein said second circuit branch further includes one or more resistors (R4, R5) coupled between the negative input terminal and the cathode terminal of an LED included in the second set of LEDs.
LED Circuit Embodiment 21. The LED circuit of LED Circuit Embodiment 7, wherein said first set of LEDs includes a first string of LEDs connected in series and said second set of LEDs includes a second string of LEDs connected in series.
LED Circuit Embodiment 22. The LED circuit of LED Circuit Embodiment 21, wherein said DC voltage is applied to a first and a second connection point to which the first and second circuit branches are coupled.
LED Circuit Embodiment 23. The LED circuit of LED Circuit Embodiment 22, wherein said first and second connection points are said positive and negative input terminals.
LED Circuit Embodiment 24. The LED circuit of LED Circuit Embodiment 23, wherein said DC voltage is received from a single power supply source.
LED Circuit Embodiment 25. The LED circuit of LED Circuit Embodiment 21, wherein said first set of LEDs includes an LED that emits light having a first color temperature and said second set of LEDs includes an LED that emits light having a second color temperature, said first and second color temperatures being different.
LED Circuit Embodiment 26. The LED circuit of LED Circuit Embodiment 21, wherein said current control circuit controls the current flow through said first and second circuit branches so that the combined light emitted from the first and second set of LEDs simulates the output of an incandescent lamp light output.
LED Circuit Embodiment 27. The LED circuit of LED Circuit Embodiment 1 wherein said LED circuit is an integrated circuit.
LED Circuit Embodiment 28. The LED circuit of LED Circuit Embodiment 1 wherein said LED circuit is implemented in an LED circuit module.
LED Circuit Embodiment 29. The LED circuit of LED Circuit Embodiment 1 wherein said LED circuit is implemented on a semiconductor chip.
LED Circuit Embodiment 30. The LED circuit of LED Circuit Embodiment 1, wherein said current control circuit comprises: at least one resistor (R2); a shunt regulator (U1); and a transistor (Q1).
LED Circuit Embodiment 31. The LED circuit of LED Circuit Embodiment 30, wherein said LED circuit is configured so that said transistor (Q1) is operated in a non-saturation amplifier mode.
LED Circuit Embodiment 32. The LED circuit of LED Circuit Embodiment 30, wherein said transistor (Q1) is operated in an amplifier mode.
LED Circuit Embodiment 33. The LED circuit of LED Circuit Embodiment 30, wherein said transistor (Q1) is operated in an active mode.
LED Circuit Embodiment 34. The LED circuit of LED Circuit Embodiment 30, wherein said transistor (Q1) is a bipolar junction transistor.
LED Circuit Embodiment 35. The LED circuit of LED Circuit Embodiment 30, wherein said transistor (Q1) is bipolar junction Negative-Positive-Negative (bjt NPN) transistor which has a saturation, cut-off, active and reverse active mode and said LED circuit is configured to operate said transistor (Q1) in said active mode.
LED Circuit Embodiment 36. The LED circuit of LED Circuit Embodiment 31, wherein said at least one resistor of said current control circuit includes at least a first resistor (R2) and a second resistor (R3), said first resistor (R2) having a first first resistor terminal and a second first resistor terminal, said second resistor having a first second resistor terminal and a second second resistor terminal; wherein said transistor (Q1) is a NPN transistor having a collector terminal, an emitter terminal and a base terminal; and wherein said shunt regulator (U1) includes a reference terminal, an anode terminal and a cathode terminal.
LED Circuit Embodiment 37. The LED circuit of LED Circuit Embodiment 5 further comprising: wherein said positive input terminal is coupled to: (i) the first set of LEDs in the first circuit branch and (ii) said current control circuit, said current control circuit being located in said second circuit branch.
LED Circuit Embodiment 38. The LED circuit of LED Circuit Embodiment 1 wherein said LED circuit of claim 1 is included in a light fixture, said light fixture including a LED drive dimmer circuit that supplies said DC voltage and an input current to the LED circuit.
LED Circuit Embodiment 39. The LED circuit of LED Circuit Embodiment 38 wherein said LED circuit is configured to operate over a DC voltage input range between 0 volts to 10 volts that is provided by said LED driver dimmer circuit.
LED Circuit Embodiment 40. The LED circuit of LED Circuit Embodiment 1 wherein said DC voltage is a dimming signal input.
LED Circuit Embodiment 41. The LED circuit of LED Circuit Embodiment 40 wherein said dimming signal input varies between 0 volts to 10 volts.
LED Circuit Embodiment 42. The LED circuit of LED Circuit Embodiment 1 in which a phase cut dimmer (TRIAC or ELV dimmer) is included in the circuitry located outside of said LED circuit that supplies power to the LED circuit.
LED Circuit Embodiment 43. The LED circuit of LED Circuit Embodiment 1 wherein said LED circuit does not include more than a single one pair input signal connection.
LED Circuit Embodiment 44. The LED circuit of LED Circuit Embodiment 1 wherein said LEDs in each of said circuit branches are in close proximity to one another so that the light emitted from the LEDs mixes.
List of Set of Exemplary Numbered Lighting Apparatus EmbodimentsLighting Apparatus Embodiment 1. A lighting apparatus comprising: a light emitting diode (LED) driver circuit having positive voltage output terminal and a negative voltage output terminal; and a light emitting diode (LED) circuit, said LED circuit comprising: two or more circuit branches coupled in parallel across the positive output terminal and the negative output terminal; each of said two or more circuit branches including a set of light emitting diodes, each of said set of light emitting diodes including at least one light emitting diode; and at least one of said circuit branches including a current control circuit that controls the current passing through each of said two or more circuit branches.
Lighting Apparatus Embodiment 2. The lighting apparatus of Lighting Apparatus Embodiment 1 further comprising: a mixer through which light emitted from LEDs included in the LED circuit passes.
Lighting Apparatus Embodiment 3. The lighting apparatus of Lighting Apparatus Embodiment 2 wherein said mixer comprises a diffused glass or plastic.
Lighting Apparatus Embodiment 4. The lighting apparatus of Lighting Apparatus Embodiment 3 wherein said LED driver circuit supplies said direct current voltage to said LED circuit.
Lighting Apparatus Embodiment 5. The lighting apparatus of Lighting Apparatus Embodiment 1 wherein said lighting apparatus includes only one LED driver circuit.
Lighting Apparatus Embodiment 6. The lighting apparatus of Lighting Apparatus Embodiment 5 wherein said LED driver circuit includes a user controlled dimmer circuit that causes a power supplied to said LED circuit to change based on a user selection.
Lighting Apparatus Embodiment 7. The lighting apparatus of Lighting Apparatus Embodiment 1 wherein said light apparatus does not use more than one LED driver circuit to supply said DC voltage and a supply current to the LED circuit.
Lighting Apparatus Embodiment 8. The lighting apparatus of Lighting Apparatus Embodiment 7 wherein said LED circuit does not include more than a single one pair input signal connection.
Lighting Apparatus Embodiment 9. The lighting apparatus of Lighting Apparatus Embodiment 1 in which a phase cut dimmer (TRIAC or ELV dimmer) is included in the LED driver circuit that supplies said DC voltage to the LED circuit.
Lighting Apparatus Embodiment 10. The lighting apparatus of Lighting Apparatus Embodiment 9 wherein said DC voltage is a dimming signal input.
Numerous additional variations on the methods and apparatus of the various embodiments described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within the scope of the invention. Numerous additional embodiments, within the scope of the present invention, will be apparent to those of ordinary skill in the art in view of the above description and the claims which follow. Such variations and embodiments are to be considered within the scope of the invention.
Claims
1. A light emitting diode (LED) circuit comprising:
- two or more circuit branches coupled in parallel across a two terminal direct current (DC) voltage input including a positive input terminal and a negative input terminal;
- each of said two or more circuit branches including a set of light emitting diodes, each of said set of light emitting diodes including at least one light emitting diode; and
- at least one of said circuit branches including a current control circuit that is configured to maintain a current passing through at least one of said two or more circuit branches in response to a decrease in DC voltage received from the two DC voltage input terminals, the control circuit consisting of:
- a first resistor;
- a second resistor;
- a shunt regulator; and
- a transistor;
- wherein:
- the two or more circuit branches include: a first circuit branch; and a second circuit branch; and
- the first and second circuit branches are coupled together only via the positive input terminal and the negative input terminal of the two terminal direct current (DC) voltage input
- wherein said first resistor has a first resistor terminal and a second resistor terminal, and said second resistor has a first resistor terminal and a second resistor terminal;
- wherein said transistor is a NPN transistor having a collector terminal, an emitter terminal and a base terminal; and
- wherein said shunt regulator includes a reference terminal, an anode terminal and a cathode terminal.
2. The LED circuit of claim 1 wherein said current control circuit controls the current flow through the second circuit branch to vary with respect to the current flow through the first circuit branch in response to a change in a value of the DC voltage.
3. The LED circuit of claim 1 wherein only one of said two or more circuit branches includes the current control circuit.
4. The LED circuit of claim 1 wherein:
- said two or more circuit branches includes only two circuit branches;
- the first circuit branch includes a first set of LEDs;
- the second circuit branch includes a second set of LEDs;
- the first circuit branch does not include the current control circuit; and
- the second circuit branch includes the current control circuit.
5. The LED circuit of claim 4 wherein said first set of LEDs includes a first string of LEDs connected in series and said second set of LEDs includes a second string of LEDs connected in series.
6. The LED circuit of claim 5 wherein said first set of LEDs includes an LED that emits light having a first color temperature and said second set of LEDs includes an LED that emits light having a second color temperature, said first and second color temperatures being different.
7. The LED circuit of claim 5 wherein said current control circuit controls the current flow through said first and second circuit branches so that combined light emitted from said first and second sets of LEDs simulate output of an incandescent lamp light output.
8. The LED circuit of claim 1 wherein said LED circuit is an integrated circuit.
9. The LED circuit of claim 1 wherein said LED circuit is implemented in an LED circuit module.
10. The LED circuit of claim 1 wherein said LED circuit is implemented on a semiconductor chip.
11. The LED circuit of claim 1 wherein said LED circuit is configured so that said transistor is operated in a non-saturation amplifier mode.
12. The LED circuit of claim 3 further wherein:
- said positive input terminal is coupled to: (i) the first set of LEDs in the first circuit branch; and (ii) said current control circuit; and
- said current control circuit is located in said second circuit branch.
13. The LED circuit of claim 1 wherein said LED circuit is included in a light fixture, said light fixture including a LED driver dimmer circuit that supplies said DC voltage and an input current to the LED circuit.
14. The LED circuit of claim 13 wherein said LED circuit is configured to operate over a DC voltage input range between 0 volts to 10 volts that is provided by said LED driver dimmer circuit.
15. A lighting apparatus comprising:
- a light emitting diode (LED) driver circuit having positive DC voltage output terminal and a negative DC voltage output terminal; and
- a light emitting diode (LED) circuit comprising two or more circuit branches coupled in parallel across the positive output terminal and the negative output terminal;
- wherein:
- each of said two or more circuit branches includes a set of light emitting diodes;
- each of said set of light emitting diodes includes at least one light emitting diode; and
- at least one of said circuit branches includes a current control circuit that is configured to maintain a current passing through at least one of said two or more circuit branches in response to a decrease in a difference between DC voltages received from the DC voltage output terminals, the control circuit consisting of: a first resistor; a second resistor; a shunt regulator; and a transistor;
- the two or more circuit branches include: a first circuit branch; and a second circuit branch; and
- the first and second circuit branches are coupled together only via the positive voltage output terminal and the negative voltage output terminal,
- wherein said first resistor has a first resistor terminal and a second resistor terminal, and said second resistor has a first resistor terminal and a second resistor terminal;
- wherein said transistor is a NPN transistor having a collector terminal, an emitter terminal and a base terminal; and
- wherein said shunt regulator includes a reference terminal, an anode terminal and a cathode terminal.
16. The lighting apparatus of claim 15 further comprising:
- a mixer through which light emitted from LEDs included in the LED circuit passes.
17. The lighting apparatus of claim 16 wherein said mixer comprises diffused glass.
18. The lighting apparatus of claim 16 wherein said mixer comprises plastic.
19. The LED circuit of claim 1 wherein said current control circuit controls the current flow through the second circuit branch to vary disproportionately with respect to the current flow through the first circuit branch in response to a change in a value of the DC voltage.
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Type: Grant
Filed: Jun 26, 2018
Date of Patent: Nov 7, 2023
Patent Publication Number: 20180376555
Assignee: Wangs Alliance Corporation (Port Washington, NY)
Inventors: Tony Wang (Sands Point, NY), Voravit Puvanakijjakorn (Port Washington, NY)
Primary Examiner: Seokjin Kim
Application Number: 16/019,467
International Classification: H05B 45/20 (20200101); H05B 45/395 (20200101);